A MECHANISTIC APPROACH TO DESIGN AND UNDERSTANDING OF HEAT RESISTANCE IN AIRFIELD PAVEMENTS

THE MECHANISM OF CONVECTIVE HEATING INDUCED SPALL FORMATION IN AIRFIELD PAVEMENTS WILL BE STUDIED. THE OBJECTIVE WILL BE TO DETERMINE THE IMPORTANT PARAMETERS RELATED TO DESIGNING HEAT RESISTANT PAVEMENTS WHILE MAINTAINING OR IMPROVING RESISTANCE TO FUEL, HYDRAULIC FLUID AND DE-ICING CHEMICALS. THE PROJECT WILL BEGIN WITH A LITERATURE REVIEW TO PREPARE A DATABASE OF HEAT RESISTANT CONCRETES AND PAVEMENT DESIGNS CURRENTLY IN USE AND TO CLASSIFY THEIR PERFORMANCE RELATIVE TO COMPOSITION. A SIMPLE CONVECTIVE HEAT TRANSFER MODEL WILL BE USED TO EXAMINE THERMAL GRADIENTS IN CONCRETES GENERATED BY TURBINE EXHAUST HEATING. THESE THERMAL GRADIENTS WILL BE USED IN A FINITE ELEMENT MODEL TO LOOK AT SIMPLE HEAT INDUCED STRESSES. ADDITIONALLY, THE EFFECT OF PORTLAND CEMENT DEHYDRATION WILL BE EXAMINED TO SEE HOW THIS AFFECTS THE BINDER AND THE BINDER AGGREGATE BOND. THE MODELING WILL BE BACKED UP BY EXPERIMENTAL TESTS TO LOOK INTO THERMAL PROFILES OF CONVECTIVELY HEATED PAVEMENTS. TESTS WILL BE CONDUCTED TO DELINEATE THE RELATIVE SIGNIFICANCE OF SIMPLE THERMAL STRESS VERSUS SHRINKAGE AND DECOMPOSITION OF THE CEMETITIOUS BINDER. THE DATABASE AND MECHANISTIC TESTING WILL BE COMPARED TO DETERMINE IF FIELD PERFORMANCE IS CONSISTANT WITH THE MECHANISTIC TESTING. FROM THIS, PAVEMENT DESIGNS WILL BE IDENTIFIED THAT MEET OR EXCEED THE THERMAL AND ENVIRONMENTAL STABILITY REQUIREMENTS.